Fuel mixture regulator for spark plug-ignited internal combustion engines

ABSTRACT

In an rpm-responsive regulator for controlling the fuel mixture, a three-dimensional cam (which, through a follower and linkage mechanism controls the fuel rack of a fuel injection pump) is displaced by integral arms of rpm-responsive centrifugal weights against the resetting force of governor springs acting through an intermediate member also displaced by the arms. For one and the same change in the pivotal position of the centrifugal weights the displacement of the three-dimensional cam is greater than the displacement of the intermediate member. This is ensured by providing that the distance of the pivotal axis of each weight from the contact area between arm and cam is - for any pivotal position of the weights - greater than the distance of said pivotal axis from the contact area between arm and intermediate member.

United States Patent [1 1 Isselhorst n11 3,766,899 51 Oct.23, 1973 [75] Inventor: I-Iartmut lsselhorst, Stuttgart,

Germany Robert Bosch GmbI-I, Stuttgart,' Germany 22 Filed: Feb. 7, 1972 211 App]. No.: 224,068

[73] Assigne e:

[30] Foreign Application Priority Data Feb 25, 1971 Germany P 21 08 824.4

[52] US. Cl.123/140 CC, 123/140 R, 123/140 MC,

907,368 2/1954 Germany 123/140 Primary Examiner Laurence M. Goodridge Assistant ExaminerRonald B. M. Cox Attorney-Edwin E. Greigg [57] ABSTRACT In an rpm-responsive regulator for controlling the fuel mixture, a three-dimensional cam (which; through a follower and linkage mechanism controls the fuel rack of a fuel injection pump) is displaced by integral arms of rpm-responsive centrifugal weights against the resetting force of governor springs acting through an intermediate member also displaced by the arms. For one and the same change in the pivotal position of the centrifugal weights the displacement of the threedimensionalcam is greater than the displacement of the intermediate member. This is ensured by providing that the distance of the pivotal axis of each weight from the contact area between arm and cam is for any pivotal position of the weights greater than the distance of said pivotal axis from the contact area between arm and intermediate member.

2 Claims, 3 Drawing Figures PAIENTEU BET 23 I973 SHEET 1B? 3 SFEET 2 [IF 3 PATENTEDBBI 2 I915 V 1 FUEL MIXTURE REGULATOR FOR SPARK PLUG-IGNITED INTERNAL COMBUSTION ENGINES BACKGROUND OF THE INVENTION This invention relates to a regulator, particularly for the control of the air-fuel mixture ratio in a spark plug ignited internal combustion engine operating on injected fuel. The regulator is of the type which has an rpm-responsive"centrifugal governor including pivotable centrifugal weights and a three-dimensional cam supported coaxiallywith the centrifugal weights and displaceable thereby in anaxial direction/The threedimensional cam is also angularly 'displaceable as a function of the position of a butterfly yalve disposed in the air intake tube of the internal combustion engine. The follower member of a transfer or linkage system is in contact with the three-dimensional cam and is actuated thereby. The transfer system controls, in response to the position of the follower member,-the position of the fuel rack of a fuel injection apparatus. Each centrifugal weight has at least one arm having two work faces. One work face of each arm engages a frontal radial face of the three-dimensional cam, while the other work face of each arm engages an intermediate member which transmits the centrifugal forces to governor springs exerting a resetting force on the threedimensional cam.

In a known regulator of the aforenoted type (such as disclosed in the Technische Berichte by Bosch GmbH, Stuttgart, Vol. 1, Issue 4, Sept. 1965, pages 21 1 and 212), the three=dimensional cam emulates the de- I which takes into account the output and fuel consumption of the engine. I

Because ofthe Clean Air laws (California test), in modern engines theperformance curve also has to take into account the permissible limit 'values concerning the proportion of pollutants in the exhaust gases. For this.reason, the performancecurvehas .to contain an exact value of the air-fuelratio even at low rpms which requires a high resolution or magnification and a greater precision-of the performance graph to be produced by the three-dimensional cam. This necessarily leads to the requirement of enlarging the useful stroke (axial shift) of the three-dimensionalcam which, in turn, leads to' the necessity of larger displacements of the components.

The axial displacement of the three dimensional cam is, in known governors, equal to the displacement of the intermediate member and thus equal to the shift of the work faces at :the arms of the centrifugal weights.

Both work faces of each arm have radii with a commonameter of the rpm-responsive centrifugal governor. An extension of the spring path while maintaining the forces approximately at the same values would lead to a larger spring length and would thus result in an enlargement of the regulator in the axial direction. Since 1 the space for the spring available in known regulators is usually already utilized in an optimal manner, this solution is not feasible. An increased pivotal angle of the centrifugal weights and thus larger centrifugal forces would even further increase this tendency. An increase of the diameter of the springs is limited by the position of rest (closed position) of the centrifugal weights.

In order to satisfy the requirement for an increased shift of the three-dimensional cam in regulators of the aforenoted type it is known to support the threedimensional cam separately fromthe rpm-responsive centrifugal governor and to transmit the axial displacement of a governor sleeve to the three-dimensional cam by means of a two-arm lever with a lever advantage. Such a device, which is disclosed, for example, in German Patent No. 416,048 and Swiss Patent No. 378,095, however, has the disadvantage that it requires substantial space and further, its structure is complex and expensive.

OBJECT AND SUMMARY OF THE INVENTION It is an object of the invention to provide an improved regulator of the aforedescribed type which ensures a high resolution of the performance graph of the engine while maintaining the same external dimensions and generally the same type of structure as in known governors.

Briefly stated, according to the invention, in the pivotal range of the centrifugal weights the contact area between the three-dimensional cam with one of the work faces of a weight arm has a greater radial distance from the pivotal axis of the centrifugal weights than the contact area between the intermediate member and the other work face of the same weight arm, and further,

. the perpendicular distance 30f the first-named contact area from the pivotal axis is at least as large as, or larger 1 than, the corresponding perpendicular distance of the The invention will be better understood, as well as I further objects and advantages will become more apparent, from the ensuing detailed specificationof a preferred, although exemplary, embodiment taken in conjunction with the drawing} I I I center so that the axial displacement is limited to the spring path-and the axial displacement of said work BRIEF DEscRIPTIoN or Til-IE DRAWING FIG. 1 is a schematic view, partially in section, of a regulator incorporating the inventionj FIG. 2 is a fragmentary sectional enlarged longitudinal view of one part of the regulator showing the centrifugal weights in their position of rest; and

FIG. 3 is a view similar to FIG. 2, showing the centrifugal weights in their extremev extended position they assume at maximum rpms.

DESCRIPTION or THE PREFERRED EMBODIMENT Turning now to FIG. 1, on a drive shaft 10 of'a fuel injection pump 11 for an Otto-engine, there is mounted an rpm-responsive centrifugal device generally indicated at 12 and including a plurality of pivotally secured centrifugal weights 13 each having an arm 14. A three-dimensional cam 15 is slidably mounted on the shaft and is urged into a continuous engagement with arms 14 by means of a compression spring 16. It is apparent that a change in the angular (pivotal) position of the weights 13 affects the axial position of the three-dimensional cam 15. In the extension of the rotational axis of the centrifugal device 12, each arm 14 engages at 18, at its side remote from the threedimensional cam 15, an intermediate member or governor sleeve 17. The latter has, remote from the location of engagement 18, a stepped spring seat 19 for the governorsprings 21, 21a and 21b. These governor springs engage at their other ends an adjusting'means 22 forming part of the centrifugal device 12.

In addition to rpm-responsive axial shifts, aided or opposed (dependent upon the direction of shift) by the regulator springs 21, 21a and 21b, the threedimensional cam is, by means of an operator lever 23, angularly adjustable through a linkage lever 24. In this manner, according to the position of the operator lever 23, different ranges of theperiphery of the threedimensional cam 15 will be aligned with a follower member 25 of a first intermediate lever 26 which forms part of a force transfer or linkage system and which has the configuration of a bell crank lever. The operator lever 23 is connected with the butterfly valve disposed in the air intake tube 20 (both shown only symbolically) of the internal combustion engine.

Axial displacements of the three-dimensional cam 15 dependent upon the rpm and angular motions thereof controlled by the operator lever 23 result, dependent upon the course of the cam track 27 aligned with the follower member 25, in a pivotal motion of the first intermediate lever 26. This motion is transmitted to a second intermediate lever 28 which has a pivot 29 affixed to the regulator housing 30. It is noted that a fixed attachment of any component to the housing 30 is indicated in a simplified manner in FIG. 1 by means of hatching. i

The second intermediate lever 28 has at one of its ends a slot 31 "into which extends a pin 32 of the first intermediate lever 26. At its other end thesecond intermediate lever 28 has a second slot 33 in which there is guided a pin 35 affixed to the fuel rack 34 of the fuel injection pump 11. Thus, displacements of the follower member are transmitted by means of the intermediate levers 26 and 28 to the fuel rack 34.

A spring 36 attached to the upper terminal portion 28a of the second intermediate lever 28 and to a pin 37 13 in their outermost position (maximum rpm). It is noted that in FIGS. 2 and 3 only one weight 13 is shown in its entirety. The arm 14 of the centrifugal weight 13 engages with an arcuate work .face 38, the intermediate member 17 at its contact area 18 (FIG. 2), 18 (FIG. 3). Remote from the work face 38, the arm 14 has a second work face 39, which engages a radial face 42 of the three-dimensional cam 15 at the contact area 41 (FIG. 2), 41' (FIG. 3). i

According to the invention, in the entire pivotal range of the centrifugal weights 13, at any given position thereof the radial distance of the pivotal axis 43 of each weight 13 from the contact area between the work face 39 of the arm 14 and the three-dimensional cam l5 is greater than the radial distance of thepivotal axis 43 from the contact area between the work face 38 and the intermediate member 17. Also, in the entire pivotal range of the centrifugal weights 13, at any given position thereof, the perpendicular distance of the pivotal axis 43 of each weight 13 from the contact area between the work face 39 of the arm 14 and the threeaffixed to the regulator housing 30, causes the follower 7 member 25 to be pressed at all times against the cam track 27.

The pivot pin 29 of the second intermediate lever 28, shown in this example as being affixed to the housing 30,'may be conventionally designed to be shiftable, dependent upon variable engine parameters, such as air pressure and coolant temperature. In this manner the position of the fuel rack 34 controlled by the threedimensional cam 15 may be corrected by a shift of the pivot pin 29.

FIGS. 2 and 3 illustrate in detail those components which are designed according to the invention or are in the vicinity thereof. In FIG. 2, the centrifugal weights 13 are shown in their innermost position (position of rest), whereas FIG. 3 illustrates the centrifugal weights dimensional cam 15 is at least as large as, or larger than, the perpendicular distance of the pivotal axis 43 from the contact area between the work face 38 and the intermediate member 17. In support of the aforenoted two comparisons it is seen in FIG. 2 that the radial distance ral between the pivotal axis 43 and the contact area 41 is greater than the radial distance rbl between the pivotal axis 43 and the contact area 18, while the perpendicular distance a1 between the pivotal axis 43 and the contact area 41 is at least as large as (in this example greater than) the perpendicular distance bl between the pivotal axis 43 and the contact area 18. Similarly, it is seen in FIG. 3 that the radial distance ra2 between the pivotal axis 43 and the contact area 41 is greater than the radial distance rb2 between the pivotal axis 43 and the counter area 18', while the perpendicular distance a2 between the pivotal axis 43 and the contact area 41' is at least as large as (in this example greater than) the perpendicular distance b2 between the pivotal axis 43 and the contact area 18'. As a result-of setting the distances ral, ra2 a1, a2, rbl, rb2', b1 and b2 in the aforenoted manner, the distance between the three-dimensional cam 15 and the intermediate member 17 will be different as the pivotal position of the weights 13 changes. It is thus seen in FIG. 2 that the distance c1 between the threedimensional cam 15 and the intermediate member 17 is greater than the distance 02 in FIG. 3. This means that for the same angular change of the weights 13 the three-dimensional cam 15 executes a stroke M which is larger than the stroke h2 of the intermediate member 17. For the purpose of clearly illustrating this stroke difference in one'and the same figure, the position as sumed by the arm in FIG. 2 is shown in FIG. 3 with phantom lines and is indicated at 14'. Thus, FIGS. 2

and 3 clearly show how an enlargedv stroke hl of the three-dimensional cam 15, thus resulting in a more accurate course of the curve track 27.

The three-dimensional .cam 15 is, as clearly shown in FIGS. 2 and 3, slidably supported on the cylindrical portion 44 of a hub member 45 which is affixed to the drive shaft and to which centrifugal weights 13 are pivotally secured. The hub member 45 has a sleeve-like part 46 in which there is guided the intermediate member 17. The latter has a stepped portion 19 which forms a spring seat for the governor springs 21, 21a and 21b. The intermediate member 17 has integral actuating arms 47 which project laterally out of the hub member 45 and are guided in openings 48 thereof. The work face 38 of each centrifugal weight 13 engages an actuating arm 47 of the intermediate member 17 at the contact area 18. i

The mode of operation of the individual components of the governor has already been discussed. In the description that follows there will be set forth the mode of operation of the entire regulator for the case when the engine, given a fixedly set operator lever 23, increases its rpm from a stand-still to a maximum value which is the case during starting.

By means of the operator lever 23, the load position shown in FIG. 1 is predetermined. Accordingly, the linkage lever 24 has rotated the three-dimensional cam 15 into its position illustrated. In this position the cam track 27, which is only one part of the entire performance curve represented by the three-dimensional cam 15, is aligned with the follower member 25, of the first intermediate lever 26. The centrifugal weights 13 assume at the standstill of the engine their innermost position as shown in FIGS. 1 and 2, while the threedimensional cam 15 assumes an axial position on the extreme left. The spring 16 is in its maximum compressed state. The distance now between the radial face 42 of the three-dimensional cam 15 and the work face 49 of an actuating arm 47 of the intermediate member 17 has a magnitude of 01. The follower member 25' is in contact with the cam track 27 at point A.

When the engine is started and its rpm increases, the

centrifugal weights 13 pivotoutwardly against the force of the governor springs 21, 21a and 21b, the intermediate member 17 is moved towards the right and the three-dimensional cam 15, urged by the spring 16, follows the arms 14 of the centrifugal weights 13. At the same time, the cam track 27 movesunderneath the follower member 25 which follows the configuration of the cam track 27 and accordingly, by means of the intermediate levers 26 and 28, the fuel rack 34 of the fuel injection pump 11 is shifted. When the engine operates with maximum rpm, the three-dimensional cam 15, the centrifugal weights 13 and the intermediate member 17 have reached their position shown in FIG. 3, at which time the follower member 25 is in contact with the cam track 27 at point B.

During the motion of the centrifugal weights 13 from the position shown in FIG.-2 into the position shown in FIG. 3, the distance between the three-dimensional cam 15 and the intermediate member 17 has decreased from 01 to c2; the work face 39 and the contact area 41, 41 have executed an axial stroke of the magnitude three-dimensional cam.

of hl, while the work face 38 and the contact area 18, 18' have executed a stroke of the magnitude of k2. Since, as it is clearly shown in FIG. 3, 01 is greater than c2 and hl is greater than h2, the three-dimensional cam 15 has, according to the invention, a greater axial stroke than the intermediate member 17.

The increase of the stroke of the three-dimensional cam 15 achieved by the particular disposition of the work faces 38 and 39 at the arm 14 of each centrifugal weight 13 is kept between bounds by the fact that the greatest possible distance of the contact area 41, 41 of the three-dimensional cam 15 from the pivotal axis 43 is limited by the outer diameter of the radial face 42 of the three-dimensional cam 15 when the centrifugal weights 13 are in their outermost position as shown in FIG. 3.

That which is claimed is:

1. In a regulator for controlling the air-fuel ratio in a spark plug-ignitedinternal combustion engine operating on injected fuel, said engine including an air intake tube and an arbitrarily operable butterfly valve disposed therein, said regulator being of the known type that has (a) rpm-responsive centrifugal weights each swingable about a pivotal axis while revolving about a rotational axis, (b) at least one arm integral with each centrifugal weight, each arm having a first work face and a second work face, (0) a three-dimensional cam supported coaxially with said rotational axis, said threedimensional can being in contact with said first work face to cause an axial displacement of said three dimensional cam by said centrifugal weights, (d) at least one governor spring opposing the axial displacement of said three-dimensional cam in response to rpm increases, (e) an axially shiftable intermediate member supported coaxially with said rotational axis and being urged against said second work face of said arm by said governor spring, (1) means for angularly displacing said three-dimensional cam as a function of the position of said butterfly valve in said air intake tube, (3 follower means in engagement with said three-dimensional cam and (h) means for transmitting the displacements of said follower means to the fuel rack of a fuel injection apparatus, the improvement comprising a first contact area defined by the engagement between said three dimensional cam and said first work face of said arm and a second contact area defined by the engagement between said intermediate member and said second work face of said arm, the radial distance of said pivotal axis from said. first contact area being, for any pivotal position of said centrifugal weights, greater than the radial distance of said pivotal axis from said second contact area and the perpendicular distance of said pivotal axis from said first contact area being, for any pivotal position of said centrifugal weights, at least as large as the perpendicular distance of said pivotal axis from said second contact area.

2. An improvement as defined in claim 1, said threedimensional cam having a radial face containing said first contact area, the maximum distance of said pivotal axis from said first contact area when said centrifugal weights are in their outermost pivotal position being limited by the outer diameter of said radial face of said 

1. In a regulator for controlling the air-fuel ratio in a spark plug-ignited internal combustion engine operating on injected fuel, said engine including an air intake tube and an arbitrarily operable butterfly valve disposed therein, said regulator being of the known type that has (a) rpm-responsive centrifugal weights each swingable about a pivotal axis while revolving about a rotational axis, (b) at least one arm integral with each centrifugal weight, each arm having a First work face and a second work face, (c) a three-dimensional cam supported coaxially with said rotational axis, said three-dimensional can being in contact with said first work face to cause an axial displacement of said three-dimensional cam by said centrifugal weights, (d) at least one governor spring opposing the axial displacement of said three-dimensional cam in response to rpm increases, (e) an axially shiftable intermediate member supported coaxially with said rotational axis and being urged against said second work face of said arm by said governor spring, (f) means for angularly displacing said three-dimensional cam as a function of the position of said butterfly valve in said air intake tube, (g) follower means in engagement with said three-dimensional cam and (h) means for transmitting the displacements of said follower means to the fuel rack of a fuel injection apparatus, the improvement comprising a first contact area defined by the engagement between said three-dimensional cam and said first work face of said arm and a second contact area defined by the engagement between said intermediate member and said second work face of said arm, the radial distance of said pivotal axis from said first contact area being, for any pivotal position of said centrifugal weights, greater than the radial distance of said pivotal axis from said second contact area and the perpendicular distance of said pivotal axis from said first contact area being, for any pivotal position of said centrifugal weights, at least as large as the perpendicular distance of said pivotal axis from said second contact area.
 2. An improvement as defined in claim 1, said three-dimensional cam having a radial face containing said first contact area, the maximum distance of said pivotal axis from said first contact area when said centrifugal weights are in their outermost pivotal position being limited by the outer diameter of said radial face of said three-dimensional cam. 